In Situ Preparation of Highly Stable Ni-Based Supported Catalysts by Solution Combustion Synthesis

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• 作者：Allison Cross ; Sergey Roslyakov ; Khachatur V. Manukyan ; Sergei Rouvimov ; Alexander S. Rogachev ; Dmitry Kovalev ; Eduardo E. Wolf ; Alexander S. Mukasyan
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：November 13, 2014
• 年：2014
• 卷：118
• 期：45
• 页码：26191-26198
• 全文大小：491K
• ISSN：1932-7455

文摘

Solution combustion synthesis (SCS) is typically used to produce nanostructured oxides and bulk metallic materials for a variety of application including catalysis. Here, we report in situ, one-step SCS of high surface area (155 m²/g) Ni catalysts supported on fumed silica (SiO₂). Time-resolved X-ray diffraction is used to investigate the dynamics of phase formation during combustion of nickel nitrate鈥揼lycine鈥揳mmonium nitrate reactive gels impregnated onto porous SiO₂. It is shown that highly dispersed nickel nanoparticles (5 nm) formed in the reaction front are followed by their rapid oxidation by air oxygen. To prevent the undesired oxidation process, the synthesis was conducted in an inert atmosphere (argon, helium). It is demonstrated that low concentration oxygen impurity (less than 0.001 wt %) in the inert gas passivates the Ni nanoparticles through the formation of a thin amorphous oxide layer. The thus prepared Ni/SiO₂ supported catalyst possesses high activity during the ethanol decomposition toward hydrogen at low temperatures (200 掳C) and excellent stability toward deactivation with essentially no change of catalyst activity over 100 h of operation.